Regeneration of functional neurons in neurodegenerative disorders or after nerve injury remains a major challenge in the neural repair field. Current efforts largely focus on cell replacement therapy using exogenous cells derived from embryonic stem cells or induced pluripotent stem cells (Buhnemann et al., 2006; Emborg et al., 2013; Nagai et al., 2010; Nakamura and Okano, 2013; Oki et al., 2012; Sahni and Kessler, 2010). Despite great potential, such cell transplantation approaches face significant hurdles in clinical applications such as potential immunorejection, tumorigenesis and differentiation uncertainty (Lee et al., 2013; Liu et al., 2013b; Lukovic et al., 2014). Further, while previous studies have shown that astroglial cells can be directly converted into functional neurons both in vitro (Guo et al., 2014; Heinrich et al., 2010) and in vivo (Grande et al., 2013; Torper et al., 2013; Guo et al., 2014), and that astrocytes can be converted into neuroblast cells and then differentiated into neuronal cells in stab-injured mouse brain (Niu et al., 2013) or spinal cord (Su et al., 2014), these approaches have the significant disadvantages of requiring viral infection inside the brain. Thus, such previous methodologies entail performing sophisticated brain surgery, intracranial injection of viral particles, and the considerable risk that is concomitant with such procedures. There is accordingly an ongoing and unmet need for new compositions and methods for regenerating functional neurons in the central or peripheral nervous system without the requirement for introducing exogenously reprogrammed cells or viral constructs into human subjects.